Kantō Plain

The Kantō Plain (関東平野 Kantō heiya) is the largest plain in Japan located in the Kanto Region of central Honshū. The total area 17,000 km² covers more than half of the Region extending over Tokyo, Saitama Prefecture, Kanagawa Prefecture, Chiba Prefecture, Gunma Prefecture, and Tochigi Prefecture.

The northern limit borders on the Abukuma Highlands, Yamizo Mountain Range, Ashio Mountain Range, and a volcanic field associated with the Nasu Volcanic Belt. The western coincides with the Kantō Mountain Range and the southern edge is defined by the Bōsō Peninsula, the Miura Hills, Tokyo Bay, and Sagami Bay. The Kashima Sea and Kujūkuri Beach define the eastern end of the plain. Most of the rivers originate in the northern or western mountain ranges and flow east or southeast into the Pacific Ocean, Tokyo Bay, or Sagami Bay. In the central part of the plain is the Tone River; in the northern part the Watarase River, Kinu River, Kokai River, Naka River, and Kuji River; and in the southern part the Arakawa River, Tama River, and Sagami River. Of these rivers, the Tone River encompasses a large area of floodplain, for it has the largest drainage area in Japan of 16,840 km². The drainage areas covered by these rivers account for the alluvial lowland of the Kanto Plain.